Need help separating fact from B.S.

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flw
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Need help separating fact from B.S.

#1 Unread post by flw »

I stopped by a Kawaski and Honda dealer to look around and pick up some supplies.

I ask the sales person if he had 10 minutes to bring me up to speed on current sport bike configurations and differences. ( I ride a small crusier) One of the things he told me is that a Inline parellel engines do not generate the rpms/HP that a v twin can in a sport configuration.

I asked how Kawaski could even compete since the line seems to all be inline parellels in the 600 cc range. He said those are racing bikes which I told him I understood. Yet if the arrangement of the pistons is keeping the ninja's power down, it would be logical that something else is going on if they can still compete.

Could someone educate me here on the why parellel twin vs the v-twin sport bike engines power bands differences. According to the sales person.
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High_Side
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#2 Unread post by High_Side »

Balance. The parrallel twin (like the Ninja 650) would shake like a paint-shaker without power-robbing balance shafts or an offset crank (not sure what the Ninja 650 uses but likely one of these methods). A 90 deg. V-twin is naturally balanced and thus resides the difference.

The "competetive" Ninjas are all in-line 4s which is why they rev higher. I think maybe you were getting confused between the two?

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Johnj
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#3 Unread post by Johnj »

BeastInBlack@rat.net wrote:A V-twin throbs and pulses, a parallel twin barks and bites .
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OreoGaborio
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Re: Need help separating fact from B.S.

#4 Unread post by OreoGaborio »

flw wrote:One of the things he told me is that a Inline parellel engines do not generate the rpms/HP that a v twin can in a sport configuration.
Now if you're only talking about the difference between a parallel twin and a v-twin then yes, the guy at the dealership, and High_Side are correct. A Parallel twin (650R) requires a bit more balancing than a V-twin (SV650) and thus will not quite put out the same kind of power, all other things being equal.

If you're talking inline 4 cylinders vs v-twins, then the guy at the dealership is incorrect... it's the other way around. Inline 4's may produce less torque, but more horsepower because they're able to spin at much higher RPM's.

Horsepower is basically a function of Torque over Time (or in the case of an engine, RPM.) In general, the faster you can make an engine spin, the more horsepower it can produce.

Just about any modern Inline 4 cylinder 600cc engine will be able to spin 14-16,000 RPM's and put out anywhere between 90 and 110hp to the rear tire.

A Suzuki SV650 or Kawi 650R in comparison, can only spin to about 10,000 RPM's and can only put out about 65-70hp to the rear wheel despite having about a 50cc advantage, but is able to produce a comparable amount of torque at a lower RPM than your typical 600.
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